Document CH399021A demonstrates an acceleration measuring device comprising a piezoelectric system, a seismic mass, a preloading sleeve, and a base plate. The piezoelectric system is mechanically preloaded between the seismic mass and the base plate by means of the preloading sleeve. During acceleration, the seismic mass exerts a force on the piezoelectric system that is proportional to its acceleration. Both positive and negative accelerations can be detected due to the mechanical preloading. The force itself generates piezoelectric charges in the piezoelectric system that can be electrically picked up as acceleration signals. These acceleration signals are proportional to the amount of the force. Acceleration signals that have been electrically picked up can be electrically amplified and evaluated in an evaluation unit.
Such an acceleration measuring instrument for measuring shock and vibration is commercially distributed by the applicant with the type designation 8002K. The acceleration measuring device is arranged in a mechanically robust housing made of stainless steel. According to data sheet No. 8002_00_205d_07.05 it has a weight of 20 grams and can be attached to any measured object by means of a mounting bolt. The measuring range is in the range of ±1000 g, the resonance frequency is 40 kHz and the operating temperature ranges from −70° C. up to +120° C.
It is a first object of the present invention to improve this well-known acceleration measuring device. Another object of the invention is to provide a cost-effective method of manufacturing such acceleration measuring instrument.